So, Rowan the Spineless has really put the proverbial cat amongst the pigeons
What I think he seems to be saying is far less radical then the headlines will no doubt say (though this is RW so he might be saying something quite different)
I think he is starting from the position that he wants to preserve some space for religious thinking alongside the secular law, which means that there may be areas where religious attitudes or regulations can run alongside the secular law. The exemptions from the SOR's given to the church would be an example of that.
I think RW is suggesting that there may be areas where Sharia law can be respected and seen as acceptable alongside secular law - for example, with regard to some areas of family law within Muslim communities, perhaps on the lines of the acceptability of the Beth Din which has control of some aspects of family law within the orthodox Jewish community ( and is respected by the state)
I think, though, that his agenda is to try and preserve a religious space given the logic of a multi-faith society is increasing secularism as no religion is given preference. i think he is worried that unless this space is given for sharia, then Christians' privileges may be lost.
My own view is that the civil law should be secular, and that means no exemptions for anyone, but I think it likely that churches and mosques alike are likely to practice that which they believe in within their own walls, which is what freedom of religion means. But if some Christians wish to see Christianity receive a privileged place, then there will also be Muslims asking for the same and in a pluralist society there is no logic in refusing. So - one law for all, no exemptions for religion. And no superior place for a church which the vast majority of citizens have no interest in attending.